The hard part: You've only got a week to build it, you know demand will be crazy.
The good news: Normal "process" is thrown out and you can do whatever you want. It just has to work.
What would you do, software and architecture wise?
PS - No, I do not work at the SBA and this isn't a hidden plea for help.
For the data entry part, a form with JavaScript (Vanilla or jQuery, no fancy frameworks like React/Vue) and a backend taking care of the data handling. Backend should be as lean as possible and supported by a load balancer for more replicas.